Multiple glazed unit



A ril 28, 1942. o. n. ENGLEHART 2,231,064

MQLTIPLE GLAZED UNIT Filed NOV. 22, 1939 i //V VE/V TOR od'cfik 0. EVGZEl/HR -r war/AL;

Patented Apr. 28, 1942 MULTIPLE GLAZED UNIT Oscar D. Englehart, Brackenridge, Pa" assignor to Pittsburgh Plate Glass Company,

County, Pa.,

Allegheny a corporation of Pennsylvania Application November 22, 1939, Serial No. 305,646

1 Claim.

The present invention relates to multiple glazed constructions and more particularly to a double glazed unit which exhibits a greater resistance to moisture penetration than the ordinary sealed, double glazed unit.

The primary object of the invention is the provision of a double glazed unit, utilizing a simple frame; wherein admission of moisture or water vapor is prevented to a marked degree. Other objects and advantages of the invention will become more apparent from the following detailed description of a preferred embodiment thereof.

Many types of double glazed units have been devised and proposed during the past years. They vary from a simple auxiliary sash designed to be affixed over a regular sash, to a complex, multiple-glazed prefabricated unit. Certain lines of development included not only sealed units but ventilated units as well. More recently dehydrating elements have been incorporated into the units in order to overcome objectionable moisture concentration therewithin, which impaired visibility through the units. Another favored modification contemplates the use of easily dismantled units in which moisture penetration is not sought to be avoided, since the units may be taken apart, cleaned, and reassembled with little effort.

Briefly stated, the present inventioncontemplates the provision of a sealed double glazed unit particularly resistant to moisture penetration because of the inclusion therein of a peripheral layer of a salt of low vapor pressure. The selected material reduces the vapor pressure diflerence between the atmosphere and the air contained in the unit and thus successfully overcomes the tendency of water vapor or moisture to infiltrate gradually into the unit in an attempt to reach a state of equilibrium. One embodimentof the invention is illustrated in the accompanying drawing, wherein:

The figure is a partial vertical sectional view of a unit constructed in accordance with the provisions of the invention.

Referring to the drawing, sheets 2 of glass are held in spaced relation by a strip 3 of rubber, syntheticresin or other resilient material positioned adjacent the peripheries of the sheets of glass. A layer 4 of a salt of a low vapor pressure, such as magnesium chloride, potassium sulfate, potassium acetate, lithium chloride, zinc chloride, aluminum chloride orsodium bromide, lies around the periphery of the assembled sheets and is retained in position by a strip I5 formed of rubber or other resilient material substantially of U-shape in cross-section. The edges of the strip 6 are of sufficient size that they extend over the outer surfaces of the glass sheets and so protect them from direct contact with a frame I, of metal or molded resin, which completes the unit.

The units are preferably fabricated by assembling the glass sheets and the spacer strip and subsequently adding thereto the frame and salt layer. The frame may be applied in sections, each of which is held horizontally in order that the salt layer may be evenly distributed throughout the length thereof, and after the frame is secured in place there'wlll be little or no possibility of movement of the salt. If it is desired, a thin coating of an adhesive or binder may be added to the strip 8 by means of which the salt layer will be held in proper position during fabrication of the unit. This latter method enables the manufacturing operations to proceed in the usual manner and requires no special apparatus.

The frame sections may be spot welded together, or where a molded frame is used, heat and pressure together with a suitable cement may be employed to seal the joints present in the frame. The unit is particularly applicable for use in combination with an interlocking frame similar to that shown in United States Patent No. 2,049,528, issued August 4, 1936, or the frame sections may be held together by a strap element as described in United States Patent No. 2,091,314, issued August 31,1937.

The units are ordinarily constructed in such fashion. that the air entrapped between the spaced sheets of glass is substantially anhydrous. The only possible manner in which water vapor may subsequently enter this air space is by infiltration through the spacer strip, separating the sheets of glass, or the joints between the spacer strip and the glass sheets, and this also entails seepage around the edges of the frame. Obviously the principal reason for this infiltration of water vapor is the considerable difference in vapor pressures between the atmosphere and the air entrapped in the unit.

When the outer air is highly humid, water vapor enters the salt layer and combines therewith rather than passing through into the closed air space. The hydrated salt still has a low vapor pressure and accordingly the differential in pressures is not sufficient to further the passage of water vapor into the unit,

Since there is no direct connection between the salt layer and the air space of the unit, there is no possibility of salt particles passing into the unit and forming a haze or translucent area upon the inner surfaces of the'glass sheets. The protecting salt layer. is used on all sides of the unit and in service temperatures of approximately 30 degrees below zero may be experienced without objectionable moisture condensation.

The benefits arising from the use of a peripheral layer of low vapor pressure salt are more noticeable when the closed air space is in direct connection with a desiccator unit. By reducing the moisture penetration into the glazing assembly, the life of the desiccant is materially increased and the moisture content of the air in the confined space is maintained at a minimum.

An experimental desiccated construction has been exposed for over ten months to an atmosphere with 57 per cent relative humidity and a temperature of 80 degrees F. and no frosting occurs at 30 degrees below zero. A similar unit without the low vapor pressure salt layer exposed under identical conditions showed frosting at approximately 5 degrees F.

It will at once be obvious that the salts of low vapor pressure other than those set forth may be used and various modifications in the frame structure are possible without departing from the spirit of the invention or the scope of the appended claim.

. What I claim is:

A double glazing unit comprising a plurality of glass plates, spacers between the plates at the margins thereof providing a dead air chamber, a frame substantially of U-shape in crosssection surrounding the glass plates, and a layer of hygroscopic material interposed between the frame and the spacers between the plates.

OSCAR n. ENGLEHARLT. 

